Question

Find the mass of ammonia in the 100 cubic feet tank having a pressure of 70 psi at 120 °F.

Answer 1

Ideal gas law

$PV=nRT \\ V=100 \;ft^3 = 2831.68 \;L\\ P=70 \;psi = 4.7632 \;atm\\ T= 120 \;°F = 322.039$

R=0.082058 L×atm/(K×mol)

$n = \frac{PV}{RT} \\ = \frac{4.7632 \times 2831.68}{0.082058 \times 322.039} \\ = 510.40 \;mol$

M(ammonia) = 17.031 g/mol

m(ammonia) $= 510.40 \times 17.031 = 8692.62 \;g = 8.692 \;kg$

Answer: 8.7 kg